One of my older lab bitches has suddenly got a small swelling about the size of a grape on the side of her mouth. It wasn't there this morning but now its sort of on/in her top lip, her teeth & gums look fine to me and I think it's more in the flesh than on the bone IYSWIM. Can't see any puncture marks inside or out.
I'm thinking she may have just knocked it? she was pokeing about the barn this morning with my dad so may have stuck her face somewhere she shouldn't.  she's fine in herself and it's not bothering her unless I prod it so I'm not too panicked but if it doesn't go down by tonight/tomorrow morning I'll have to take her in. (I only saw it about 1/2 hour ago btw) I'll take her back to work with me this avo so I can keep an eye on it.
Any ideas?

Have a look at my post about Moose as her lump appeared very suddenly ! Luckily is was just a benign lump. I wonder though if your girls could be an absess. Is the lump quite soft to the touch or hard as Mooses was hard as did try and squeeze it to see if any puss would come out.

thanks, that was quick!
It feels quite weird when I squeeze it, the best I can describe is like a small tight wad of tissues. it could be sort of solid pus, but I wouldn't have thought it would go hard this quickly if it was an absess? (sp?) I would have expected it to be fluid filled first.

I've been watching your posts, hope your girl is soon on the mend.

One of my dogs gets something similar as a reaction to a tick.  I notice you mentioned no obvious puncture wound but I've never seen them either, even when I've taken the tick off and looked. 

Watch and wait might be the best advice, for now,  but you could wash/wipe with Hibiscrub and give Piriton if you suspect a bite

well it's a little bigger now and there is a small reddish spot starting to look a bit unpleasant in the middle. So I think a tick (though she's had ticks before and never reacted) or maybe an insect sting might be the answer. before when I said no puncture wounds I was wondering if she'd met a rat or something, didn't think of a sting. unfortunately I don't have either Hibiscrub or Piriton, I'd never heard of them before browsing on here a few weeks ago and have been meaning to look for some. That'll teach me to be more organised! I'll give it a clean with TCP or salt warm water in a bit and see in the morning.  on the plus side, she's still happy as Larry and it doesn't seem to hurt, she scrunched up her chicken wings for dinner without a wince.
thanks for the help